Whats the lowest I can drop a 1979 long bed Chevy with still good clearance?

[Chevycruisin88]

Hey guys Im new to the whole thread thing and Im wanting to get some feedback from people that have been there and done it to avoid the headaches, and wasting money on things that wont work right out the gate.
So first off I got my grandpas old 1979 3/4 ton camper special with the 454 and the turbo 400 transmission that Ive had in storage since the transmission blew. The motor only has 90k original miles on it and I got a buddy giving me a turbo 400 with about 50k on it to swap out the old one with. I plan on totally rebuilding this truck, not restore but fully customize to my liking. Its 2wd and I want to drop it but not slam it....

1.So my first question is how low can I drop it and still have decent ground clearance? (Not hitting speed bumps, and dragging on the road if I hit a pothole) I want to put at least 20's on it but probablly no bigger then that because I like some rubber.
2. Also Im going to be installing a pretty decent sized blow through sub box in the back of the bed for those that are familiar with systems and am trying to decide if a snugtop will be my best bet, or the fabricated one that sits flush with the sides of the bed...(not sure what its called and if that is just sheet metal then bondoed or what) but if I go with the one that sits flush can I install hydraulic jacks like a snugtop and still be able to access my bed as well if I went that route?

3. Im still debating if I go with shaved handles or not but Ive heard you get into issues with the poppers giving you problems... but thats also something Id like a little input on?

I'll have tons more questions down the road but didnt want to overwhelm anybody. Im just new to all of this and this whole build will take some time because I'm going to be doing everything myself and short on cash so Ive been doing all the research I can before I start wrenching away on this bad boy. Once I get the truck towed over here to the house to start working on it I will post some pics for you guys as well. Thanks for your time and any input you might have would be greatly appreciated!
Thanks
Cody